Electric switch and arc extinguishing method



Sept. 29, 1931. T. T. GREENWOQD ELECTRIC SWITCH AND ARC EXTINGUISHING METHOD Original Filed Dec. 1, 1926 Patented Sept. 29, 1931 'GJNHTED STATES PATENT OFFICE TALMA T. GREENWOOD, OF EAST TEMPLETON, MASSACHUSETTS, ASSIGNOR TO CONDUIT ELECTRICAL MANUFACTURING CORPORATION, OF SOUTH BOSTON, MASSACHUSETTS,

A CORPORATION OF MASSACHUSETTS ELECTRIC SWITCH AND ARC EXTINGUISHING METHOD Application filed December 1, 1926, Serial No. 152,049. Renewed January 21, 1930.

This invention relates to electric switches and has for an object the provision of electrostatic means to extinguish the circuit interrupting are combined with means providing a pressure chamber in which the circuit interrupting arc is drawn.

A further object of the invention is generally to improve the construction and operation of electric switches.

The idea of extinguishing a circuit interrupting are by an electrostatic field is disclosed in my co-pendingapplication Serial No. 152,048, filed December 1, 1926.

Fig. 1 is a sectional elevation taken through an electric switch embodying the invention.

Fig. 2 is an enlarged sectional elevation taken through the arc extinguishing chamber carried by one of the switch terminals.

Fig. 3 is a diagrammatic representation of the electric circuits of the invention.

The electric switch embodying this invention comprises an enclosing casing adapted to be filled with some suitable arc quenching and electrically insulating liquid as oil to some level 12. Switch terminals comprising conducting studs 14 and insulators 16 for said studs are carried by the cover 18 of said casing and depend into the oil therein. Each stationary switch member is provided with a stationary arcing member and pressure chamber and means to establish an electrostatic arc-extinguishing field in the vicinity of the arcing member. The parts associated with but one switch terminal need be described.

An attaching plate-120 is secured by a nut 22 to the lower end of the switch terminal and is electrically connected with the stud 14 thereof. Said plate is provided with one or more depending arms 24 which are integral with a substantially horizontal disc-shaped plate 26. Said plate is provided with an internally screw-threaded aperture in the middle thereof in which an upstanding bushing 28 is screw-threaded. The open upper end of said bushing has a cap 30 removably connected therewith. A segmental tubular contact or arcing member 32 is disposed beneath said cap 30 and the segments thereof are connected to said cap by spring members 34. A metal bowl 36 surrounds sald plate 26 and said arcing member and forms a strong pressure-retaining chamber 1n which the circuit interrupting arc is adapted to be drawn. Said bowl 36 is provlded with an integral bottom wall 38 having an opening 40 in the bottom thereof. A.

the circuit interrupting arc is adapted to be drawn. The bottom wall of said insulating bowl is provided with an aperture 46 through which the movable contact or arcing member is adapted to be passed.

Said metal bowl is adapted to be secured rigidly to and electrically insulated from said plate 26. To this end a plate of insulating material 48 is disposed on the top plate 26 and a metel clamping ring 50 is in internally screw-threaded engagement with the upper end of said bowl'36 whereby to clamp said bowl to said plate 26 through the medium of said insulating plate 48 and said insulating bowl 4.2.

Themovable switch member comprises a switch operating rod 52 which carries a horizontally disposed conducting bar 54 at its lower end. Movable contact or arcin members 56 com rising vertically exten ed cylindrical rods are secured to the ends of said bars 54 in position to enter the apertures 56 in the bottom walls of the pressure chambars and make contact with the stationary contact members 32.

In accordance with this invention, said howls 36 are utilized to setup an electrostatic field in the vicinity of the circuit interrupting arcs between said stationary and movable contact members whereby to extinguish the arcs. To this end each switch terminal is provided with a current transformer 58 at its lower end which transformer is well known in the art and comprises an iron core, and a secondary winding, the primary comprising the stud of the switch terminal. One terminal. 60 of the current transformer is connected with the at taching fied without departing members in a closel plate 20 and thereby electrically with the stationary contact member. The other terminal 62 of the secondary transformer is connected electrically with the insulated metal bowl 36 by means of the screw 64. The metal bowl therefor is adapted to be at a different potential than the arcing members. If, for instance, the stationary arcing member happens to be negative the connections of the transformer are so arranged that the bowl is made more negative than the arc member. Under this condition, the negative electrons in the arc stream will be repelled away from the movable contact member and the circuit interrupting arc will thereby be extinguished. v

Pressure or explosion chambers per se are old in the art. These chambers, however, usually have been electrically connected with the stationary switch member by which they have been supported and so have not been adapted to make use of the principle herein set forth.

The pressure or explosion chamber serves to confine the gases and pressure that may result from the drawing of the arc and the electrostatic field of the chamber serves to extinguish the are rapidly.

This invention in one aspect consists in insulating the explosion chamber from its associated contact member and electrifying said chamber at a potential which is difierint from the potential of said arcing mem- The construction ma be otherwise modiom the spirit of the invention.

I claim:

1. The method of interrupting an electric circuit which consists in drawing a circuit interrupting are between separable contact confined fluid body, and subjecting the circuit interru ting arc to the arc extinguishing action 0 an electrostatic field which is at a potential that is diflerent from the are potential.

2. The method of extinguishing a circuit interrupting are which consists in subjecting the arc to the combined action of fluid pressure and'an electrostatic field which is at a potential that is different from the arc potential.

3. The method of interrupting an electric circuit which consists'in drawing a circuit interrupting are between separable contact members in a closely confined fluid body, and simultaneously subjecting the circuit interrupting arcto the extinguishing action of fluid pressure and to an electrostatic ,field which is at a potential that isdiflerent from the are potential.

4. The method of extinguishing an electric are which consists in establishing the arc in a pressure resistant chamber which is also the source of an electrostatic field that is at a potential that is different from the arc potential and which acts on the arc to extinguish it.-

5. An electric switch having the combination of a pressure resist-ant chamber, contact members separable therein and means including said chamber providing an arcextinguishing electrostatic field in the region including said arcing members.

6. An electric switch having the combination of a pressure resistant chamber, contact members separable therein, and means to electrify said chamber at a potential different from the potentials of said contact members.

' 7. An electric switch having the combination of a pressure resistant chamber having a metal wall, contact members separable therein, means to insulate said chamber from said contact members, and means to apply a potential to said chamber which is different from the potentials of said contact members.

8. An electric switch having the combination of a pressure resistant chamber having a metal wall, contact members separable therein, means to insulate said chamber from said contact members, and means to ap ly a potential to said chamber which is di erent from the potentials of said contact members, said means comprising a current transformer energized from the circuit of said contact members.

9. An electric switch having the combination of an insulated switch terminal, a stationary contact member carried at the lower end thereof, a conducting pressure resisting chamber surrounding said contact member and having insulating means connecting it mechanically with said switch terminal, a contact member movable in and out of said chamber in cooperative relation with the aforesaid contact member, and means to apply a potential to said chamber difierent from the potentials of said contact members.

10. An electric switch having the combination of an insulated switch terminal, a stationary contact member carried at the lower end thereof, a conducting pressure resisting chamber surrounding said contact member and having insulating means connectin it mechanically with said switch termina a contact member movable in and out of said chamber in cooperative relation with the aforesaid contact member, and means to apply a potential to said chamber different from the potentials of said contact members, said means including a current transformer carried by said switch terminal and having its winding connected to said switch terminal and also to said conducting chamber.

11. An electric switch having the combination of a switch member provided with a contact member, an insulated casing enclossurrounds said opening,

' tials of said contact members to ing said switch member and having an opening therein, a mo-vable'contact member movable through said opening into and out of engagement with said first contact member, said casing having a conducting part which surrounds said opening, and means to apply a potential that is different from the potentials of said contact members to said conductin part.

12. in electric switch having thev combination of a switch member provided with a contact member, an insulated casing enclosing said switch member and having an opening therein, a movable contact member movable through said opening into and out of engagement with said first contact member, said casing having a conducting part which surrounds said opening, and means to apply a potential that is different from the potentials of said contact members to said conducting part, said means including a transformer which is energized from said switch circuit.

13. An electric switch having the combination of a switch member provided with a contact member, an insulated casing enclosing said switch member and having an opening therein, a movable contact member movable through said opening into and out of engagement with'said first contact member, said casing having a conducting part which surrounds said opening, and means a potential that is different from the potensaid conducting part, said means including a transformer which is energized from said switch circuit and has a connection with said first contact member and another connection with said conducting part.

A, An electric switch having the combination of a switch member provided with a contact member, an insulated casing enclosing said switch member and having an open ing therein, a movable contact member movable through said opening into and out of engagement with said first contact member, said casing having a conducting part which and means to apply a potential that is different from the potentials ofsaid contact members to said conducting part, said means including a current transformer which has series with the switch circuit and a secondary which is connected between said first contact member and said conducting part.

15. An electric switch having the combination of a switch member provided with a contact member, an insulated casing encl0sing said switch member and having an opening therein, a movable contact member movable through said opening into and out of engagement with said first contact member,

sald casing having a conducting part which surrounds said openilillg, and means to apply a potentialthat is di erent from the potento applyv a primary in &

tials of said contact members to said con at an electrostatic ion controlling electric potential surrounding one of said contact members and located adjacent the zone of the arc in positionto act thereon and to effect the extinguishment of the are and the interruption of the circuit.

17. An electric switch having separable contact members between which an arc is drawn, and electric-ally energized means which is at an ion controlling electric po tential and which surrounds one of said contact members and is located adjacent the zone of the arc in position to act thereon and effect the extinguishment of the arc and the interruption of the circuit.

18. An electric switch having separable contact members between which an arc is drawn, means which is at an electric poten tial that is different from the potential of said contact members and which surrounds one of said contact members and is located adjacent the zone of the arc in position to act thereon and effect the extinguislnnent of the arc and the interruption of the circuit, and means to apply a potential to said first means, which potential is derived from the switch circuit.

lln testimony whereof, I have name to this specification.

TALMA T. GREENWOGDQ signed my CERTIFICATE OF CORRECTION.

Patent No. 1,825,228. Granted September, 1931, to

TALMA r. GREENWQOD.

' It is hereby certified that the name of patent was erroneously written and printed as "Conduit Electrical Manufacturing Corporation", whereas said name should have been written and printed as Condit "ElectricalManufacturing Corporation, as shown by the reco rds of assignments in this office; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in Signed and sealed this 17th day of November, A. D. 1931.

the assignee in the above numbered M. J. Moore, (Seal) Acting Commissioner of Patents.

the Patent Office. 

